Republican candidates past and present were out on the stump today, as Dr. Ben Carson threw his support behind former rival Donald Trump. Carson’s endorsement followed an unusually civil GOP debate Thursday night. Meanwhile, Sen. Marco Rubio doubled down on campaigning efforts in his home state of Florida while Hillary Clinton left the trail to attend Nancy Reagan’s funeral.

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HARI SREENIVASAN:

Republican candidates past and present were out on the stump today, all eyes are on key states, like Florida and Ohio, set to vote in the primary on Tuesday.

DONALD TRUMP (R), Republican Presidential Candidate: I just want to introduce Dr. Ben Carson, a special, special person, a special man.

BEN CARSON (R), Former Republican Presidential Candidate: There are two different Donald Trumps. There's the one you see on the stage, and there's the one who is very cerebral, sits there and considers things very carefully. You can have a very good conversation with him. And that's the Donald Trump that you're going to start seeing more and more of.

DONALD TRUMP:

Ben, thank you.

HARI SREENIVASAN:

Trump embraced the endorsement and said it was a sign Republicans are getting behind his campaign.

DONALD TRUMP:

I have been hearing from virtually everybody in the Republican Party, and they are congratulating me. And they are saying, we're going to get together.

HARI SREENIVASAN:

He was coming off yet another Republican debate, where the tone shifted to near civility, dialing back on the bravado.

DONALD TRUMP:

And so far, I cannot believe how civil it's been up here.

(LAUGHTER)

HARI SREENIVASAN:

But his rivals weren't willing to concede anything. Ohio Governor John Kasich leads in the polls in the Buckeye State, one of five holding their primaries next Tuesday.

GOV. JOHN KASICH (R-OH), Republican Presidential Candidate: Well, first of all, let's not — you know, math doesn't tell the whole story in politics. You have to earn the delegates in order to be picked. But let's not get ahead of ourselves. We don't know what's going to happen, because we still have about half the delegates to be selected. And that's what's going to be a very interesting thing to see how it all turns out as we move forward over the next couple of weeks.

HARI SREENIVASAN:

Texas Senator Ted Cruz argued only he has the chance to beat Trump.

SEN. TED CRUZ (R-TX), Republican Presidential Candidate: There are only two of us that have a path to winning the nomination, Donald and myself. At this point, I have roughly 360 delegates. He has about 100 more than I have. We have at this point beaten Donald in eight separate states all over the country

DONALD TRUMP:

I watch Ted on television and when he speaks, and he's always saying, "I'm the only one that beat Donald in six contests, and I beat him."

But I beat him in 13 contests. He never mentions that.

(CHEERING AND APPLAUSE)

HARI SREENIVASAN:

Trump also responded to violence against protesters at his rallies, including one assault caught on videotape Wednesday.

JAKE TAPPER, CNN:

Some of your critics point to quotes that you have made at these debates — at these rallies, including February 23, "I would like to punch him in the face," referring to a protester, February 27, "In the good old days, they'd have ripped him out of that seat so fast," February 1, "Knock the crap out of him, would, you? Seriously, OK, just knock the hell — I promise you I will pay for the legal fees. I promise, I promise."

HARI SREENIVASAN:

Trump didn't condone the violence, but said:

DONALD TRUMP:

We had a couple big, strong, powerful guys doing damage to people, not only the loudness — the loudness, I don't mind — but doing serious damage. And if they have got to be taken out, I — to be honest, I mean, we have to run something.

HARI SREENIVASAN:

And today at Trump's rally in Saint Louis, protesters employed a new tactic, staggering their interruptions one at a time throughout Trump's remarks.

DONALD TRUMP:

We better get our country going, folks, because that's the kind of stuff — it's taking us down. It's taking us down fast.

HARI SREENIVASAN:

Florida Senator Marco Rubio urged voters to consider the impact of their choices on Tuesday and how to vote in both his home state and in Ohio.

SEN. MARCO RUBIO (R-FL), Republican Presidential Candidate: If a voter in Ohio is motivated by stopping Donald Trump and comes to the conclusion that John Kasich is the only one who can beat him there, then I expect that is the decision they will make. I can tell you that, in Florida, I'm the only one that can stop Donald Trump, and whether someone supports Ted Cruz or John Kasich,, if you vote for them in Florida, you're in essence voting for Donald Trump.

And if a voter reaches the same conclusion in Ohio, then I think that's what they're going to do as well.

HARI SREENIVASAN:

Without wins in their home states, Rubio and Kasich face the end of the road for their runs.